Gaia project at ARI

The Gaia mission is an astrometric space observatory of the European Space Agency (ESA) to survey and map the positions, distances, motions, and brightness of over a billion stars in our Milky Way galaxy. The mission was launched in December 2013 and is still ongoing. The data collected by Gaia is used to study the formation and evolution of our galaxy, as well as the properties of stars, planets, and other celestial objects.

Up to now three versions of the Gaia catalogue have been published:

• Gaia Data Release 1 (Gaia DR1): This release, which occurred in September 2016, included positions and magnitudes (brightness) for about 1.1 billion stars and two thousand quasars. For more than two million stars also parallaxes (from which distances can be calculated), and proper motions were included. Additionally, light curves for about 3000 stars were published. The data released in Gaia DR1 were collected during the first 14 months of the Gaia mission, from July 2014 to September 2015.
• Gaia Data Release 2 (Gaia DR2): This release, which occurred in April 2018, included positions, magnitudes, and colours for almost 1.7 billion stars. For 1.3 billion stars, parallaxes, proper motions are included. Additionally, Gaia DR2 also contains radial velocities for more than seven million stars, astrometric data for 14,000 solar system objects, and a catalogue of half a million variable stars. The data released in Gaia DR2 were collected during the first 22 months of the Gaia mission, from July 2014 to May 2016.
• Gaia Data Release 3 (Gaia DR3): The data released in GDR3 were collected during the first 32 months of the Gaia mission, from July 2014 to May 2018. The release has been split into two parts: The Early Data Release 3 , which occurred in December 2020, already contained the astrometric and photometric data for single stars. The rest of the data was published in June 2022. DR3 contains positions, magnitudes, and colours for 1.8 billion stars, for almost 1.5 billion stars also  parallaxes and proper motions. Gaia DR3 also includes radial velocities for more than 33 million stars, object classifications for 1.5 billion stars, as well as a catalogue of about ten million variable stars, more than 800 thousand binary systems, more than six million quasar candidates, 900 thousand galaxy candidates,  almost 160 thousand solar system objects. For the first time, also more than 200 thousand low-resolution spectra, and almost one million high-resolution spectra were published.

The scientific data reduction for the Gaia mission is being prepared by the pan-European Data Processing and Analysis Consortium (DPAC, external link).

At ARI DR1 and DR2 are available on http://gaia.ari.uni-heidelberg.de